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March 3, 1959. H. J. HAMPEL 2,876,425

PULSE TRANSFORMER ASSEMBLY Filed Aug. 31. 1953 i5 42 ein '42 FIC-3.3

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nited States Patent PULSE TRANSFORHWER ASSEMBLY Herbert L Hampel, Philadelphia, Pa., assigner to Burroughs Corporation Detroit, Mich., a corporation of Michigan Application August 31, 1953, Serial No. 377,358

d Claims. (Cl. 336-198) This invention relates to the housing or packaging of small electrical units and particularly to improved packaging for magnetic units, crystals and similar electrical components.

For certain applications of such units, and particularly pulse transformers, it is deemed desirable to provide a housing to allow rougher handling, and to prevent accidental breakage or dislodgment of the delicate leads associated with the components. ln the past pulse transfoi-mers have been housed by molding a housing with a potting compound which encapsulates the transformer upon hardening. This encapsulating method requires a mold to form the housing and the cost of the mold and the steps involved in the molding process add materially to the cost of manufacturing a housed unit of this character. Abe realized in the packaging or housing of pulse transformers and the like by providing a suitable cup shaped member or bottie cap as the housing. The bottle cap not only acts as housing or protecting shell but also as a mold for the potting compound which upon hardening seals the pulse transformer within the cap. The cost of. providing a mold is thereby eliminated along with the steps involved in the molding process. This not only provides a less expensive assembly operation but also has the added advantages of providing a more durable and stable unit.

It is, therefore, a general object of the invention to provide an improved packaged unit for electrical components.

It is another important object of the invention to provide an improved pulse transformer sub-assembly housed in a protecting enclosure of a bottle cap design.

It is a further important object of the invention to provide an improved pulse transformer unit which is capable of being easily and economically assembled with a minimum of skill.

It is still another important object of the invention to provide an electrical unit comprising a pulse transformer packaged in a suitable bottle cap housing which is capable of rapid and economical fabrication and results in a more stable and permanent unit.

The above and related objects are achieved by providing a suitable cup shaped member of bottle cap design as a housing for a pulse transformer' subassembly along with novel external output leads. The leads are shaped to prevent accidental breakage of the small internal transformer connections joined thereto, and of suilicient strength to allow the transformer to be wired to its associated circuitry much like a small capacitor or resistor. Provisions are also made for separately identifying each of the transformer leads for testing and for rapid assembly. Upon sealing the transformer sub-assembly within the housing by a potting compound, a more stable and permanent unit results.

Other objects and features of advantage of the present invention will be found throughout the following more lt has been found that considerable savings may ICC detailed description of invention particularly when considered with the accompanying drawings in which like reference characters refer to similar elements:

Fig. l is an exploded perspective view of a pulse transformer constructed in accordance rwith the invention showing the various elements in the order of their assembly; t

Fig. 2 is a plan view of the pulse transformer subassembly constructed in accordance with the invention with the housing removed; and

Fig. 3 is a cross-sectional view partly broken away, of the assembly constructed in accordance with the invention to show the lead pin arrangement.

Referring now to Fig. 1, the various elements and their inter-relationship will be described with reference to the details illustrated in Figs. 2 and 3 for clarilication. The pulse transformer sub-assembly 8 is made up of the insulating, non-magnetic bobbin lil enclosed by a pair of mating, identical magnetic core pieces 12 and 14 made of a magnetic material such as ferrite or a similar material. The core pieces 12 and 14 are aligned and secured together by a non-magnetic screw 16 which fits through the axially aligned apertures of the cores 12 and 14 and the aperture 18 of the bobbin 10. It is preferred to abut the cores in end to end relationship in order to minimize the possibilities of an air gap between the adjacent surfaces of the core pieces effecting the desirable flux pattern. The periphery of the bobbin 10 is provided with one or more recessed sections or channels 2t) upon which the electrical conductive windings 22 and 24 are pre-wound. The magnetic core pieces 12 and 14 are preferably shaped as shown in Fig. 1 with recessed inner end faces to receive and enclose the bobbin 16. Only the internal structural arrangement of the magnetic core 14 is visible in the exploded view illustrated in Fig. l, but it is understood that core 1'2 is likewise similarly internally arranged. The cores 12 and 14 are preferably substantially circular in outline and each is provided with a notch identied respectively at 2S and 26 extending vertically along a portion of their respective outer periphery. The inner end face of each core is formed with an annularly shaped concavity 27 between a centrally located apertured projection or boss 28 and the outer periphery of the core. The bosses 28 are adapted to enter the aperture 13 of the bobbin 1d when the bobbin is positioned within the concavities of the cores. lt will be understood that the bosses 25 abut one another when the vcores 12 and 14 are in assembled relationship and constitute a post extending through the enclosure formed by the concavities 27' of said cores. When the core pieces are so positioned the pre-wound electrical leads 22 and 2d are arranged to be wididrawn through the notches 2S and 26 onto the relatively flat outer end face of the core 12. The assembly is preferably completed by a disc 3i) which is provided with a central hole 32 for vreceiving the screw 16 and is secured against the outer end face of the core 14 by means of a nut 33 threaded on the screw. The disc 3l) is provided with an outside diameter slightly greater than those of the cores. in lieu of the nut 33, the disc may be internally threaded for direct threaded engagement with the screw.

The ferrite cores 12 and 14 being electrically conductive, the outwardly extending portions of the windings 22 and 24 are provided with an insulation which, in this instance, may be color coded for rapid identification of the individual windings. The opposite end sections of the windings are each electrically connected to an electrically conductive pin. Since there are two windings in the illustrated embodiment of the invention there are four pins provided. These pins are generally identified in the drawing by reference characters 34, 36, 38 and 46,

These pins are preferably similarly formed as shown. Each pin has an elongatedsubstantially straight portion 42 connected to the extremity of one of the legs of a U- shaped portion 44. The elongated portion of each pin preferably extends approximately perpendicular to the plane of the U-shaped portion. The pins are usually placed with the U-shaped portions bearing fiat against the outer sides of the cores and resting on the projecting edge of the insulating disc 30 as more clearly seen in Fig. 3. The U-shaped portions of pins are so dimensionally related to the cores that in this position the closed ends of the pins project above the core l2 as shown in Fig. 3 and 4form convenient loops to which the end sections 22 and 24 ofthe windings are attached as shown in Fig. 2. The U-shaped portions 42 of the pins minimizes the breakage of the electrical connection thereto and by relatively closely hugging the magnetic cores they restrain rotation of the pins and any twisting or bending mo tion imparted to the pin is not transmitted to the transformer lead connection. The straight portions 42 of the pins are brought out the side of the unit to allow it to be wired or soldered into electrical receptacles or associated circuitry. However, it should be understood that the pins may be made to extend straight through the disc 30 for mounting in a socket or the like with like mechanical provisions being made to prevent breakage of the electrical connection.

To insulate the pins from the magnetic cores an electrical insulating strip or tape 46 Yis provided between the pins and the core. Preferably, the tape should be of a type, such as glass, which provides protection against burning when soldering the transformer connections as well as provide electrical insulation. Holding the pins closely against the transformer sub-assembly 8 is a wide, elasticlike band 48 which closely hugs the periphery of subassembly 3. The band 48 is normally of a smaller diameter than the outer diameter of the magnetic cores so that normal stretching would not allow it to pass over the cores. It has been found that if the band is made of a vinyl plastic and it is immersed in a suitable liquid such as toluene, the band can be stretched sufficiently to allow it to pass over the cores and the U-shaped portions of the pins and upon drying the band will tend to shrink back to its normal shape thereby holding the pins tightly against the transformer sub-assembly.

The sub-assembly 8 including the pins 34-40 is inserted into an enclosure preferably inthe form of a cupshaped member. For this purpose, it has been discovered that a conventional bottle cap serves as an excellent housing. Such a cap is generally identified by the reference character 50 and includes the closed end S2 and a slightly flaring circular side wall 54. The disc 3!) is so designed lthat it wedgingly engages the outer end of the wall 52 to completely enclose the sub-assembly within the cap. In those constructions where the pin sections 42 project laterally from the unit, it is preferred to provide notches such as indicated at 56 to permit such sections to extend through the wall of the cap. To permanently seal the sub-assembly into the bottle cap a potting compound indicated at 58 such as an epoxy resin or the like may be introduced into the cap and upon drying it tends to hermetically seal the sub-assembly within the cap. The screw 16 protrudes from the disc 3tl and may be employed to mount the completed assembly on a panel or to ground the core.

' It has been found desirable for ease in assembling the unitl to provide identification numerals on the topmost portion 52 of the cap 50, such as indicated by the numerals 1, 2, 3, 4 thereon. These numerals may be made to correspond to the coding provided for the insulation of the transformer windings previously mentioned. As an example, suppose the lead 22 is coded red and corresponds to the numeral 1, it is merely necessary for the assembler to align thel cap so that the lnotch corresponding to the l straddles the pin connected to the red coded transformer lead. In this manner a rapid external means of lead identification is provided.

It is, therefore, clear from the foregoing description that the present invention has advanced the state of the art by providing a compact packaged unit which entails a novel mechanical construction capable of rapid assembly. The internal sub-assembly is so designed that it is readily enclosed in a conventional bottle cap which serves as a protecting shell therearound. The transformer parts are assembled, the leads coded for rapid identification, and the transformer is tested prior to potting it in the cap. Novel means are provided for restraining the output leads against breakage of the electrical connection due to twisting or turning.

Having therefore described detailed embodiments of the invention and setting forth its organization, those features believed descriptive of the nature of the invention are defined in the appended claims.

What is claimed is:

l. A magnetic core assembly comprising a pair of core members of magnetic material having surface areas secured together in abutting relationship, said members being so shaped that together they form an enclosure, a post extending through said enclosure, an electrically non# conductive and non-magnetic bobbin having a plurality of spaced grooves positioned in said enclosure surrounding said post, and electrical windings disposed in each of said grooves of said bobbin, said windings including terminal ends extending exteriorly of said enclosure.

2. A magnetic core assembly comprising a pair of core members of magnetic material having surface areas secured together in abutting relationship, said members being so shaped that together they form an enclosure, a post extending through said enclosure, an electrically nonconductive and non-magnetic bobbin having a plurality of spaced grooves positioned in said enclosure surrounding Said post, electrical windings disposed in each of said grooves of said bobbin, said windings including terminal ends extending exteriorly of said enclosure, electrically conductive pins connected to said terminal ends, each of said pins including a first portion of its length positioned adjacent the external surfaces of said core members and having a second portion extending away from said cores, insulating means interposed between said pins and the outer surfaces of said core members, and means securing said rst portions of said pins against said insulating means in close proximity to the outer surfaces of said cores.

3. A magnetic core assembly comprising a pair of core members of magnetic material having surface areas secured together in abutting relationship, said members being so shaped that together they form an enclosure, a post extending through said enclosure, an electrically nonconductive and non-magnetic bobbin having a plurality of spaced grooves positioned in said enclosure surrounding said post, electrical windings disposed in each of said grooves of said bobbin, said windings including terminal ends extending exteriorly of said enclosure, electrically conductive pins connected to said terminal ends, each of said pins including a first portion of its length positioned adjacent the external surfaces of said core members and having a second portion extending away from said cores, insulating means interposed between said pins and the outer surfaces of said core members, means securing said lirst portions of said pins against said insulating means in close proximity to the outer surfaces of said cores, a cup shaped member enclosing said assembly with said second pin portions extending therefrom, and means sealing the open end of said cup.

4. A pulse transformer assembly comprising a pair of core halves of magnetic material abutting one another and preformed to provide a cavity therein, an electrically nonconductive and non-magnetic bobbin having a plurality of spaced grooves positioned in said cavity, electrical windingsdisposed-in each of said grooves and including-'terminal ends extending outside of said cores, a non-magnetic disc, means securing said core halves and said bobbin in alignment upon one side of said disc, a plurality of electrically conducting pins, each connected to a terminal end of said windings, said pins each including a U- shaped portion extending substantially parallel to the axis of said cores and a second portion extending away from said cores, insulating means interposed between said pins and the outer surfaces of said core members, a resilient member of insulating material surrounding said core to urge said U-shaped pin portions against said insulating means in close proximity to said core halves, and a cap member cooperating with said disc to enclose said assembly with said second pin portions extending from the enclosure.

References Cited in the le of this patent a UNTTED STATES PATENTS 1,763,115 Wermine June 10, 1930 2,130,815 Riepka Sept. 20, 1938 2,630,560 Earl et al. Mar. 3, 1953 10 FOREIGN PATENTS 267,619 Great Britain Mar. 2l, 1927 

